Tuesday, October 29, 2013

The Khan Academy and AAMC Teach Evolution in Preparation for the MCAT

Ross Firestone is a 2nd year MD/PhD student at the Albert Einstein College of Medicine. He is one of the winners of the MCAT Video Competition. Apparently the Khan Academy and the Association of American Medical Colleges were impressed with his presentations on evolution. You can see all six videos at Evolution and population dynamics.

I'm posting the first one on Evolution and Natural Selection. It's all about natural selection but it's a very strange kind of natural selection. The organisms are parthenogenic and each individual is genetically programed to have a certain probability of reproducing. One type has a 50% probability of reproducing and another type has only a 25% probability of reproducing. These probabilities seem to be independent of any competition between them. Each successful individual produces four offspring. After some time the number of one type remains constant (25% probability) but the number of the other type (50% probability) doubles with each generation. This is natural selection according to Ross Firestone.

"Naturally," I was disappointed that natural selection was the only mechanism mentioned. There's nothing about random genetic drift in this video and nothing about the stochastic nature of natural selection. But my face lit up when I saw that there was another video on "Alternative Selection: Learn about driving forces of evolution other than natural selection." This could almost make up for screwing up the description of natural selection.

Alas, the second video is even worse. The "alternatives" are group selection and artificial selection. It gets even more worse. The example of group selection is the grandmother hypothesis. According to Ross Firestone, the fact that grandmothers help their grandchildren survive is group selection.

The video on "Bottlenecks and the environment" is also quite interesting. I didn't know that that the peppered moth story is an example of a bottleneck. Did you?

I think these videos are horrible—so horrible, in fact, that the Khan Academy should take them down. What do you think?

Are you wondering why a 2nd year med student feels so confident that he knows enough about evolution to teach it to pre-med students? Me too.

15 comments
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Parthenogenesis is actually "Step 2". Ross Firestone begins by telling the viewers how the long-legged guy escapes the bear and finds a long-legged mate (what if he should find a short-legged one?), and they have long-legged children "because the trait is genetic" (what about dominance?). Then Firestone looks at the problem "again but more deeply", which means forgetting about sexual reproduction entirely. It's a total mess.

They are just kids teaching kids. They know nothing about evolution except what they memorized from a few books. They know nothing about how to critize it and defeat it as a option for biological complexity and diversity in the universe.Kids becoming doctors are useless to investigation of the very complicated concepts of biology.I suspect, just suspect but don't know, that the reason for this kid winning is because of a establishment desire to defend evolution from the attacks its been getting.I'm suspicious they are all in on this need to confirm evolutions truth and this sways votes.Population changes has nothing to do with the claims of evolution about everything. Its minor events in species. its no more then saying rich guys get the better looking girls and make better looking kids. Fine but its the extrapolation from this to explain bugs becoming buffalos.

We are eagerly waiting for a YouTube presentation by Robert Byers: Just So Stories Rewritten: How the Kangaroo Got His Pouch (Not always was the Kangaroo as now we do behold him...). Featuring also a short talk by Ken Ham, Esq., and clips from The Ark Vision.

You joke, but I concur. I was in an anatomy/cell bio program in a medical school. I took several classes alongside medical students - in fact we took the same first year classes they did, and we took those classes with them (we then went back to our department and had additional lectures that the medical students did not). Bunch of egomaniacs - I'd say about 70% of them felt that they were head and shoulders above not just non-medical students, but above their instructors as well.

The Khan Academy seems serious and has an infrastructure for making excellent educational material, but it needs assistance in quality control. If these videos are any indication, confusion is currently its primary product.

The evolution videos are good technically, but, as Larry strongly implies, are scientific failures. The one on “Bottlenecks and the Environment,” besides erroneously projecting industrial melanism as a bottleneck event (I've never, never seen that tried before), makes the following red-herring, no brainer, teleology accommodating statement (at 1:10): “the more traits in the gene pool, the more likely the species will survive.” This makes it sound like variability is “for” the survival of the species and that variability is “good” for its own sake. Counter examples is easy to imagine: the non-survival of populations derived from the crossing of individuals with diverse congenital defects or hybridized plant ecotypes that evolved to live under extremely specialized conditions (I do not know if either has ever be done). Either of these strategies to increase variability would be unlikely to promote “the survival of the species”.

At 2:40 there is a confusion between ‘stress’ and ‘catastrophe’ (the latter best applies), but this is somewhat corrected at 4:25 when terms ‘cataclysm’ and ‘huge stress’ are used.

I don’t have the nerve to view the other videos, so will take Larry’s word on them. Biologists residing near the Khan Academy should extend a hand of help to these well meaning people.

I just watched the video on natural selection. Ignoring the intended audience for the moment, it did convey the essence of change in a population caused by differential survival. By ignoring the complications of sexual reproduction and the genetic basis of the trait, longer legs, it got to the heart of the matter. In fact, I think it pretty accurately represents the state of knowledge of most college students after their intro biology course. Whether this is sufficient to pass the MCAT I don't know. It certainly isn't sufficient for a more than rudimentary understanding of evolution. In fairness, I didn't look at all the evolution videos. Perhaps, taken together, they might do a better, more comprehensive job.

You weren't paying attention. The essence of natural selection is, indeed, differential survival. In a mixed population of individuals with long legs and short legs the ones with long legs are more likely to survive than the ones with short legs. Eventually the allele for long legs will become fixed in the population and the allele for short legs will be eliminated.

The essence of natural selection is competition for limited resources. Usually this means a relatively constant population size.

In the example shown, the short legs get away form the bear 25% of the time and that isn't affected by how many long legs there are in the population. The long legs escape 50% of the time no matter what the proportion of short legs in the population.

Each survivor produces four offspring so the total number of short legs in the population remains constant over, say, twenty generations. Meanwhile the population of long legs has increased one million times but 50% of them are still eaten by the bears. Presumably, the bear population has also increased by the same amount.

It's true that the frequency of the short leg allele in the population has decreased and the frequency of the long leg allele has increased but it's not a very realistic example of natural selection.

It would be better to say that 75% of the population is killed by bears every generation. If you have long legs you are more likely to be among the survivors than if you have short legs. Thus, over time, the proportion of survivors with long legs increases at the expense of survivors with short legs until eventually the entire population consists of long-legged individuals and the size of the population remains constant.

I think it pretty accurately represents the state of knowledge of most college students after their intro biology course.

That's very sad. I expect every student to know about alleles, population size, probabilities, mutation, recombination, homozygous vs heterogygous, Hardy-Weinberg, population genetics, random genetic drift, speciation, and fitness (and more). If this is the state of knowledge expected of university science students in America then things are far worse than I thought.

The Khan Academy approach to teaching is an attractive one. But Khan does not have a monopoly. With Camtasia Studio software it is not difficult for contributors to this blog to prepare videos that may compete effectively with those the AAMC has solicited from the Khan Academy. My modest efforts in this respect were posted two years ago but have attracted little interest.

If this is the state of knowledge expected of university science students in America then things are far worse than I thought.I didn't say expected -- I said that it was what most college students remember after their intro course. I agree that it is sad. (I'm talking about non-majors, but even majors have inadequacies in their understanding, especially if their only exposure to population genetics/evolution is their intro course.)

Laurence A. Moran

Larry Moran is a Professor in the Department of Biochemistry at the University of Toronto. You can contact him by looking up his email address on the University of Toronto website.

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Quotations

The old argument of design in nature, as given by Paley, which formerly seemed to me to be so conclusive, fails, now that the law of natural selection has been discovered. We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man. There seems to be no more design in the variability of organic beings and in the action of natural selection, than in the course which the wind blows.Charles Darwin (c1880)Although I am fully convinced of the truth of the views given in this volume, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as "plan of creation," "unity of design," etc., and to think that we give an explanation when we only restate a fact. Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject the theory.

Charles Darwin (1859)Science reveals where religion conceals. Where religion purports to explain, it actually resorts to tautology. To assert that "God did it" is no more than an admission of ignorance dressed deceitfully as an explanation...

Quotations

The world is not inhabited exclusively by fools, and when a subject arouses intense interest, as this one has, something other than semantics is usually at stake.
Stephen Jay Gould (1982)
I have championed contingency, and will continue to do so, because its large realm and legitimate claims have been so poorly attended by evolutionary scientists who cannot discern the beat of this different drummer while their brains and ears remain tuned to only the sounds of general theory.
Stephen Jay Gould (2002) p.1339
The essence of Darwinism lies in its claim that natural selection creates the fit. Variation is ubiquitous and random in direction. It supplies raw material only. Natural selection directs the course of evolutionary change.
Stephen Jay Gould (1977)
Rudyard Kipling asked how the leopard got its spots, the rhino its wrinkled skin. He called his answers "just-so stories." When evolutionists try to explain form and behavior, they also tell just-so stories—and the agent is natural selection. Virtuosity in invention replaces testability as the criterion for acceptance.
Stephen Jay Gould (1980)
Since 'change of gene frequencies in populations' is the 'official' definition of evolution, randomness has transgressed Darwin's border and asserted itself as an agent of evolutionary change.
Stephen Jay Gould (1983) p.335
The first commandment for all versions of NOMA might be summarized by stating: "Thou shalt not mix the magisteria by claiming that God directly ordains important events in the history of nature by special interference knowable only through revelation and not accessible to science." In common parlance, we refer to such special interference as "miracle"—operationally defined as a unique and temporary suspension of natural law to reorder the facts of nature by divine fiat.
Stephen Jay Gould (1999) p.84

Quotations

My own view is that conclusions about the evolution of human behavior should be based on research at least as rigorous as that used in studying nonhuman animals. And if you read the animal behavior journals, you'll see that this requirement sets the bar pretty high, so that many assertions about evolutionary psychology sink without a trace.

Jerry Coyne
Why Evolution Is TrueI once made the remark that two things disappeared in 1990: one was communism, the other was biochemistry and that only one of them should be allowed to come back.

Sydney Brenner
TIBS Dec. 2000
It is naïve to think that if a species' environment changes the species must adapt or else become extinct.... Just as a changed environment need not set in motion selection for new adaptations, new adaptations may evolve in an unchanging environment if new mutations arise that are superior to any pre-existing variations

Douglas Futuyma
One of the most frightening things in the Western world, and in this country in particular, is the number of people who believe in things that are scientifically false. If someone tells me that the earth is less than 10,000 years old, in my opinion he should see a psychiatrist.

Francis Crick
There will be no difficulty in computers being adapted to biology. There will be luddites. But they will be buried.

Sydney Brenner
An atheist before Darwin could have said, following Hume: 'I have no explanation for complex biological design. All I know is that God isn't a good explanation, so we must wait and hope that somebody comes up with a better one.' I can't help feeling that such a position, though logically sound, would have left one feeling pretty unsatisfied, and that although atheism might have been logically tenable before Darwin, Darwin made it possible to be an intellectually fulfilled atheist

Richard Dawkins
Another curious aspect of the theory of evolution is that everybody thinks he understand it. I mean philosophers, social scientists, and so on. While in fact very few people understand it, actually as it stands, even as it stood when Darwin expressed it, and even less as we now may be able to understand it in biology.

Jacques Monod
The false view of evolution as a process of global optimizing has been applied literally by engineers who, taken in by a mistaken metaphor, have attempted to find globally optimal solutions to design problems by writing programs that model evolution by natural selection.